For the production of chemical products from biomass, various methods have been suggested such as entirely biological methods using anaerobic fermentation, and mixed methods in which intermediates obtained through biological pretreatment are chemically converted into high value-added products. On the whole, the application of biological methods to biomass means that hydrocarbons obtained from biomass by pretreatment are converted by microbial fermentation. For example, carbohydrates in biomass are converted into fermentable sugars from which ethanol, butanol, organic acids, and various amino acids can be produced by ethanol fermentation. As such, various attempts have been made to utilize biomass-derived compounds in producing higher value-added materials. Most biomass-derived compounds are obtained with an excess of water contained therein, that is, as an aqueous solution. In order to produce a target compound, water is usually separated before subsequent conversion reactions. However, the separation of water requires a significant amount of energy and additional processes, which is undesirable in view of process efficiency and economy.
Typically, benzene/toluene/xylene, known as high value-added aromatic products, are generally produced by hydrotreating and extracting pyrolysis gasoline. The production of benzene/toluene/xylene, together with basic fraction products such as ethylene, propylene and the like, occurs during the thermal cracking process of naphtha, or by catalytically reforming naphtha to form reformates, followed by separating them. In the case of using naphtha, which is produced with a narrow boiling point range in an atmospheric distillation process, conventional production techniques of aromatic products cannot smoothly respond to increasing demand. Meanwhile, the production of aromatic products from raw petroleum materials is highly apt to be accompanied with the production of environmental pollution due to a significant content of impurities such as sulfur, nitrogen, etc. in the raw materials.
To avoid this problem, the use of biomass in producing aromatic products, particularly BTX products, has been attempted. For example, biomass is thermally decomposed, and the pyrolyzates are reacted in the presence of a catalyst to yield olefins and aromatics (Korean Patent Unexamined Application Publication No. 2012-0104520). In this regard, catalytic fast pyrolysis (CFP) has been suggested as an advanced process. According to CFP, biomass is fed into a fluidized bed reactor where pyrolysis is conducted to form a pyrolysis steam, followed by introducing the pyrolysis steam into the zeolite catalyst bed in the fluidized bed reactor to produce aromatics and olefins.
In this context, the present applicant suggested a method in which ketone compounds are converted from mixed organic acids and then prepared into fuels, lubricant base oils, and aromatics through catalytic reactions (Korean Patent No. 2012-41578). The method disclosed in this patent reference is a technique for producing various hydrocarbons from ketone compounds by condensation, hydrogenation, and/or hydrodeoxygenation in the presence of a hydrogenation catalyst. Particularly since presenting a reaction mechanism by which a series of catalytic reactions can be conducted even in an aqueous solution, the method can bring about an improvement in process yield and economy. As is identified in the Examples thereof, the final product obtained by the method contains paraffins at a content of about 90 mol % or more, but aromatics at a level as low as impurities (around 5 mol %). Accordingly, the method is substantially directed toward the preparation of fuels and lubricant base oils made of paraffins, but is difficult to apply to improvement in the yield of aromatics.
As such, there is a need for a detailed technique (e.g., controlling catalyst and process conditions) by which the production yield of aromatics can be improved to a degree of significance on the basis of a reaction route feasible even in an aqueous solution.